(a) Field of the Invention
This invention relates to the technical field of inkjet printers configured to pull a sheet of printing paper out of a paper storage, feed the sheet of printing paper to a printing part and print on a printing surface of the sheet in the printing part.
(b) Description of the Related Art
Generally, inkjet printers used for photo printing systems comprise a paper storage in which a sheet or sheets of printing paper are set and a transport line for pulling the sheet of printing paper out of the paper storage and transporting it to a printing part.
The transport line in the inkjet printer of such kind is generally composed of a plurality of rollers for carrying a sheet of printing paper as disclosed in, for example, Japanese Unexamined Patent Publication No. 2003-237156.
In many inkjet printers of the above kind, printing is made on various types and formats of printing papers of different sizes. If in such cases the inkjet printer includes a single paper storage, the type or format of printing paper to be set in the paper storage must be changed according to need. To eliminate such inconvenience, like conventional photofinishing systems, inkjet printers of the above kind include two or more paper storages and are configured to selectively pull an appropriate format of printing paper out of the associated paper storage according to order information and feed it to the printing part (see, for example, Japanese Unexamined Patent Publications Nos. 2000-352766, 2001-33889 and 2002-90904).
In the transport line composed of a plurality of rollers as described above, the position of printing paper being transported changes more as the length of the transport line is increased because of individual differences or mounting errors of the rollers. Particularly, the printing paper being transported tends to change its orientation with respect to the direction of transport and its position in the width direction. Therefore, there exists a demand to minimize the length of the transport line composed of a plurality of rollers.
If the inkjet printer includes two or more paper storages as described above, two or more upstream transport lines are needed to pull various types or formats of printing papers out of the paper storages, respectively. In this case, in order to avoid that the two or more upstream transport lines significantly differ from one another in condition of printing paper being transported, it is desired to make the upstream transport lines equal in length or the number of rollers. In other words, it is desired to make the upstream transport lines equal in the position of printing paper being transported to the printing part (i.e., the orientation thereof with respect to the direction of transport and the position thereof in the width direction).
Even if, however, the above demands for the entire transport line and the upstream transport lines are satisfied in the inkjet printer of the above kind, this restricts the arrangement of paper storages and the arrangement of upstream transport lines, resulting in upsized inkjet printer.